A typical lever-type electrical connector includes an assembly of a first connector or housing and a second connector or header. To mate the connectors together, the assembly has an actuating or assist lever mounted for pivoting on the first connector with pivoting of the lever causing the first and second connectors to shift between unmated and fully mated configurations. To this end, the actuating lever and the second connector typically have a cam groove and a cam follower arrangement for drawing the second connector into mating condition with the first connector in response to pivoting of the lever. Such connectors are commonly used in the automotive industry; however, other uses are also possible.
A typical configuration for such lever-type electrical connectors is to provide a generally U-shaped lever structure having a pair of relatively thin walled lever arms that are disposed on opposite sides of the housing connector. The lever arms may have cam grooves for engaging cam follower projections or posts on opposite sides of the header assembly. These types of lever connectors are often used where relatively large forces are required to mate and unmate a pair of connectors. For instance, frictional forces encountered during connecting and disconnecting the connectors may make the process difficult to perform by hand. In some cases, relatively large electrical connectors with high pin counts, such as connectors with 90 or more pin contacts, require at least about 300 N to mate or un-mate the connectors. On the other hand, automotive industry standards specify a maximum of 75 N of user input force be required to perform this mating and un-mating of the connectors.
It has been found that current lever-actuator configurations can not effectively mate or un-mate large connectors such as described above while keeping user input force at or below the level specified by the industry standard. With current lever connector configurations, the mechanical advantage provided by the lever actuators is not sufficient to overcome the high frictional forces seen by large electrical connector assemblies between pins and sockets of the connectors as they are mated and un-mated. At the interface between the cam projection and grooves, there are inefficiencies generated in the force transfer between the input force applied to the lever and the output force applied by the lever to the other connector requiring greater efforts by the user than as desired for mating and unmating the connectors together.
U.S. Pat. No. 6,099,330 to Gundermann et al. discloses an electrical connector assembly having a lever for mating and unmating electrical connectors. However, the connector of the '330 patent is disclosed as being used with a connector assembly with only 38 contacts, which is less than half the number of pin contacts employed in the large electrical connector assemblies described above. The configuration of the interface between the cam of the lever and the camming surface of the header electrical connector of the '330 electrical assembly connector is not suitable for larger connectors because the lever does not generate a sufficient mechanical advantage using only 75 N or less of input force to shift the connectors to a mated position relative to each other. The connector assembly in the '330 patent employs an assist lever with curved cam engagement surfaces. Such a curved surface does not provide a fixed contact location between the curved cam surface of the lever and cam surface area of the header connector as the lever is pivoted, but instead generates a rolling action in the cam surface area so that the leverage and output force generated by pivoting of the lever for mating the connectors together is variable. This makes precision design of such a lever to provide the mechanical advantage necessary for mating of large connector assemblies extremely difficult. In addition, the variable engagement of the curved cam force transmitting surfaces generates an inefficient transfer of forces therebetween. This variable and rolling engagement between the lever and cam surface area typically will not generate the concentrated, high levels of output forces (e.g., greater than 300 N) with relatively low actuator forces applied to the lever (e.g., 75 N or less).
In many cases, it can be necessary for the actuating lever to be locked in an initial or pre-mate position so that the actuating lever is properly aligned for assembly of the electrical connectors. By locking the lever in such a position, the connectors can be mated without having to reposition the actuating lever to this aligned position for connector mating. Current connector configurations, such as the lever design in the '330 patent, utilize a flexible or resilient portion on the lever itself at the ends of relatively thin arms thereof to lock the lever in the pre-mate position. In order to release the lever, the resilient end portions of the lever arms are flexed or bent away from their locked position so that the lever is free to pivot. Since the thin lever arms are used to generate the output force for mating and unmating the connectors, generally it is undesirable to have these lever arms be flexed or deformed during pivoting of the lever actuator.
Accordingly, there is a need for a lever actuator for an electrical connector assembly that generates a more efficient mechanical advantage, particularly with large electrical connectors that require the lever actuator to be able to generate large output forces without requiring large input actuator forces on the lever. In addition, a lever actuator that is not deformed as it is pivoted would be desired.